Moni nonse, dzina langa ndine Sasha, ndimatsogolera kuyesa kwa backend ku FunCorp. Ife, monga ena ambiri, takhazikitsa ntchito yomanga nyumba. Kumbali imodzi, izi zimathandizira ntchitoyo, chifukwa ... Ndikosavuta kuyesa ntchito iliyonse padera, koma kumbali ina, pakufunika kuyesa kuyanjana kwa mautumiki wina ndi mzake, zomwe nthawi zambiri zimachitika pa intaneti.
M'nkhaniyi, ndilankhula za zida ziwiri zomwe zingagwiritsidwe ntchito kuyang'ana zochitika zoyambira zomwe zimafotokoza momwe mungagwiritsire ntchito pulogalamuyo pamaso pamavuto amtaneti.
Kutengera zovuta za netiweki
Nthawi zambiri, mapulogalamu amayesedwa pa maseva oyesera omwe ali ndi intaneti yabwino. M'malo ovuta kupanga, zinthu sizingakhale zosalala, choncho nthawi zina muyenera kuyesa mapulogalamu osalumikizana bwino. Pa Linux, chidachi chimathandizira ndi ntchito yofananiza mikhalidwe yotere tc.
tc (abbr. kuchokera ku Kuwongolera Magalimoto) amakulolani kuti mukonzekere kutumiza mapaketi a netiweki mudongosolo. Chida ichi chili ndi kuthekera kwakukulu, mutha kuwerenga zambiri za iwo . Pano ndingoganizira zochepa chabe za izo: timakondwera ndi ndondomeko ya magalimoto, yomwe timagwiritsa ntchito qdisc ndi, ndipo popeza tifunika kutsanzira netiweki yosakhazikika, tidzagwiritsa ntchito classless qdisc .
Tiyeni tiyambitse seva ya echo pa seva (ndinagwiritsa ntchito ):
ncat -l 127.0.0.1 12345 -k -c 'xargs -n1 -i echo "Response: {}"'
Kuti ndiwonetse mwatsatanetsatane ma timestamp onse pagawo lililonse lolumikizana pakati pa kasitomala ndi seva, ndidalemba chosavuta cha Python chomwe chimatumiza pempho. mayeso ku seva yathu ya echo.
Kodi source source
#!/bin/python
import socket
import time
HOST = '127.0.0.1'
PORT = 12345
BUFFER_SIZE = 1024
MESSAGE = "Testn"
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
t1 = time.time()
print "[time before connection: %.5f]" % t1
s.connect((HOST, PORT))
print "[time after connection, before sending: %.5f]" % time.time()
s.send(MESSAGE)
print "[time after sending, before receiving: %.5f]" % time.time()
data = s.recv(BUFFER_SIZE)
print "[time after receiving, before closing: %.5f]" % time.time()
s.close()
t2 = time.time()
print "[time after closing: %.5f]" % t2
print "[total duration: %.5f]" % (t2 - t1)
print data
Tiyeni kukhazikitsa ndi kuyang'ana pa magalimoto pa mawonekedwe lo ndi port 12345:
[user@host ~]# python client.py
[time before connection: 1578652979.44837]
[time after connection, before sending: 1578652979.44889]
[time after sending, before receiving: 1578652979.44894]
[time after receiving, before closing: 1578652979.45922]
[time after closing: 1578652979.45928]
[total duration: 0.01091]
Response: Test
Kutaya kwa magalimoto
[user@host ~]# tcpdump -i lo -nn port 12345
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
10:42:59.448601 IP 127.0.0.1.54054 > 127.0.0.1.12345: Flags [S], seq 3383332866, win 43690, options [mss 65495,sackOK,TS val 606325685 ecr 0,nop,wscale 7], length 0
10:42:59.448612 IP 127.0.0.1.12345 > 127.0.0.1.54054: Flags [S.], seq 2584700178, ack 3383332867, win 43690, options [mss 65495,sackOK,TS val 606325685 ecr 606325685,nop,wscale 7], length 0
10:42:59.448622 IP 127.0.0.1.54054 > 127.0.0.1.12345: Flags [.], ack 1, win 342, options [nop,nop,TS val 606325685 ecr 606325685], length 0
10:42:59.448923 IP 127.0.0.1.54054 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 606325685 ecr 606325685], length 5
10:42:59.448930 IP 127.0.0.1.12345 > 127.0.0.1.54054: Flags [.], ack 6, win 342, options [nop,nop,TS val 606325685 ecr 606325685], length 0
10:42:59.459118 IP 127.0.0.1.12345 > 127.0.0.1.54054: Flags [P.], seq 1:15, ack 6, win 342, options [nop,nop,TS val 606325696 ecr 606325685], length 14
10:42:59.459213 IP 127.0.0.1.54054 > 127.0.0.1.12345: Flags [.], ack 15, win 342, options [nop,nop,TS val 606325696 ecr 606325696], length 0
10:42:59.459268 IP 127.0.0.1.54054 > 127.0.0.1.12345: Flags [F.], seq 6, ack 15, win 342, options [nop,nop,TS val 606325696 ecr 606325696], length 0
10:42:59.460184 IP 127.0.0.1.12345 > 127.0.0.1.54054: Flags [F.], seq 15, ack 7, win 342, options [nop,nop,TS val 606325697 ecr 606325696], length 0
10:42:59.460196 IP 127.0.0.1.54054 > 127.0.0.1.12345: Flags [.], ack 16, win 342, options [nop,nop,TS val 606325697 ecr 606325697], length 0
Chilichonse chiri chokhazikika: kugwirana chanza katatu, PSH / ACK ndi ACK poyankha kawiri - uku ndiko kusinthanitsa kwa pempho ndi kuyankha pakati pa kasitomala ndi seva, ndi FIN / ACK ndi ACK kawiri - kukwaniritsa kugwirizana.
Kuchedwa kwa paketi
Tsopano tiyeni tiyike kuchedwa kukhala 500 milliseconds:
tc qdisc add dev lo root netem delay 500ms
Timatsegula kasitomala ndikuwona kuti zolembazo zikuyenda kwa masekondi a 2:
[user@host ~]# ./client.py
[time before connection: 1578662612.71044]
[time after connection, before sending: 1578662613.71059]
[time after sending, before receiving: 1578662613.71065]
[time after receiving, before closing: 1578662614.72011]
[time after closing: 1578662614.72019]
[total duration: 2.00974]
Response: Test
Kodi mumagalimoto muli chiyani? Tiyeni tiwone:
Kutaya kwa magalimoto
13:23:33.210520 IP 127.0.0.1.58694 > 127.0.0.1.12345: Flags [S], seq 1720950927, win 43690, options [mss 65495,sackOK,TS val 615958947 ecr 0,nop,wscale 7], length 0
13:23:33.710554 IP 127.0.0.1.12345 > 127.0.0.1.58694: Flags [S.], seq 1801168125, ack 1720950928, win 43690, options [mss 65495,sackOK,TS val 615959447 ecr 615958947,nop,wscale 7], length 0
13:23:34.210590 IP 127.0.0.1.58694 > 127.0.0.1.12345: Flags [.], ack 1, win 342, options [nop,nop,TS val 615959947 ecr 615959447], length 0
13:23:34.210657 IP 127.0.0.1.58694 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 615959947 ecr 615959447], length 5
13:23:34.710680 IP 127.0.0.1.12345 > 127.0.0.1.58694: Flags [.], ack 6, win 342, options [nop,nop,TS val 615960447 ecr 615959947], length 0
13:23:34.719371 IP 127.0.0.1.12345 > 127.0.0.1.58694: Flags [P.], seq 1:15, ack 6, win 342, options [nop,nop,TS val 615960456 ecr 615959947], length 14
13:23:35.220106 IP 127.0.0.1.58694 > 127.0.0.1.12345: Flags [.], ack 15, win 342, options [nop,nop,TS val 615960957 ecr 615960456], length 0
13:23:35.220188 IP 127.0.0.1.58694 > 127.0.0.1.12345: Flags [F.], seq 6, ack 15, win 342, options [nop,nop,TS val 615960957 ecr 615960456], length 0
13:23:35.720994 IP 127.0.0.1.12345 > 127.0.0.1.58694: Flags [F.], seq 15, ack 7, win 342, options [nop,nop,TS val 615961457 ecr 615960957], length 0
13:23:36.221025 IP 127.0.0.1.58694 > 127.0.0.1.12345: Flags [.], ack 16, win 342, options [nop,nop,TS val 615961957 ecr 615961457], length 0
Mutha kuwona kuti kuyembekezera kwa theka la sekondi kwawonekera pakulumikizana pakati pa kasitomala ndi seva. Dongosololi limachita mosangalatsa kwambiri ngati kutsalira kuli kwakukulu: kernel imayamba kutumizanso mapaketi ena a TCP. Tiyeni tisinthe kuchedwa kukhala 1 sekondi ndikuyang'ana kuchuluka kwa magalimoto (sindiwonetsa zotuluka za kasitomala, pali masekondi 4 omwe akuyembekezeka nthawi yonse):
tc qdisc change dev lo root netem delay 1s
Kutaya kwa magalimoto
13:29:07.709981 IP 127.0.0.1.39306 > 127.0.0.1.12345: Flags [S], seq 283338334, win 43690, options [mss 65495,sackOK,TS val 616292946 ecr 0,nop,wscale 7], length 0
13:29:08.710018 IP 127.0.0.1.12345 > 127.0.0.1.39306: Flags [S.], seq 3514208179, ack 283338335, win 43690, options [mss 65495,sackOK,TS val 616293946 ecr 616292946,nop,wscale 7], length 0
13:29:08.711094 IP 127.0.0.1.39306 > 127.0.0.1.12345: Flags [S], seq 283338334, win 43690, options [mss 65495,sackOK,TS val 616293948 ecr 0,nop,wscale 7], length 0
13:29:09.710048 IP 127.0.0.1.39306 > 127.0.0.1.12345: Flags [.], ack 1, win 342, options [nop,nop,TS val 616294946 ecr 616293946], length 0
13:29:09.710152 IP 127.0.0.1.39306 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 616294947 ecr 616293946], length 5
13:29:09.711120 IP 127.0.0.1.12345 > 127.0.0.1.39306: Flags [S.], seq 3514208179, ack 283338335, win 43690, options [mss 65495,sackOK,TS val 616294948 ecr 616292946,nop,wscale 7], length 0
13:29:10.710173 IP 127.0.0.1.12345 > 127.0.0.1.39306: Flags [.], ack 6, win 342, options [nop,nop,TS val 616295947 ecr 616294947], length 0
13:29:10.711140 IP 127.0.0.1.39306 > 127.0.0.1.12345: Flags [.], ack 1, win 342, options [nop,nop,TS val 616295948 ecr 616293946], length 0
13:29:10.714782 IP 127.0.0.1.12345 > 127.0.0.1.39306: Flags [P.], seq 1:15, ack 6, win 342, options [nop,nop,TS val 616295951 ecr 616294947], length 14
13:29:11.714819 IP 127.0.0.1.39306 > 127.0.0.1.12345: Flags [.], ack 15, win 342, options [nop,nop,TS val 616296951 ecr 616295951], length 0
13:29:11.714893 IP 127.0.0.1.39306 > 127.0.0.1.12345: Flags [F.], seq 6, ack 15, win 342, options [nop,nop,TS val 616296951 ecr 616295951], length 0
13:29:12.715562 IP 127.0.0.1.12345 > 127.0.0.1.39306: Flags [F.], seq 15, ack 7, win 342, options [nop,nop,TS val 616297952 ecr 616296951], length 0
13:29:13.715596 IP 127.0.0.1.39306 > 127.0.0.1.12345: Flags [.], ack 16, win 342, options [nop,nop,TS val 616298952 ecr 616297952], length 0
Zitha kuwoneka kuti kasitomala adatumiza paketi ya SYN kawiri, ndipo seva idatumiza SYN / ACK kawiri.
Kuphatikiza pa mtengo wokhazikika, kuchedwa kutha kukhazikitsidwa kuti apatukane, ntchito yogawa, ndi kulumikizana (ndi mtengo wa paketi yapitayi). Izi zimachitika motere:
tc qdisc change dev lo root netem delay 500ms 400ms 50 distribution normal
Apa takhazikitsa kuchedwa pakati pa 100 ndi 900 milliseconds, zikhalidwe zidzasankhidwa molingana ndi kugawa kwanthawi zonse ndipo padzakhala kulumikizana kwa 50% ndi kuchedwa kwa paketi yapitayi.
Mwinamwake mwazindikira kuti mu lamulo loyamba limene ndinagwiritsa ntchito kuwonjezerakenako kusintha. Tanthauzo la malamulowa ndi lodziwikiratu, kotero ndingowonjezera kuti pali zina ndi, zomwe zingagwiritsidwe ntchito kuchotsa kasinthidwe.
Kutayika Kwa Paketi
Tiyeni tsopano tiyese kuchita kutayika kwa paketi. Monga momwe tingawonere kuchokera ku zolembazo, izi zikhoza kuchitika m'njira zitatu: kutaya mapaketi mwachisawawa ndi mwayi wina, pogwiritsa ntchito unyolo wa Markov wa 2, 3 kapena 4 kuti muwerenge kutayika kwa paketi, kapena kugwiritsa ntchito chitsanzo cha Elliott-Gilbert. M'nkhaniyi ndikambirana njira yoyamba (yosavuta komanso yodziwika bwino), ndipo mukhoza kuwerenga za ena .
Tiyeni tiwononge 50% yamapaketi okhala ndi 25%:
tc qdisc add dev lo root netem loss 50% 25%
Mwatsoka, wcputu sitingathe kutiwonetsa bwino kutayika kwa mapaketi, tidzangoganiza kuti zimagwiradi ntchito. Ndipo nthawi yowonjezereka komanso yosakhazikika ya script idzatithandiza kutsimikizira izi. client.py (itha kumalizidwa nthawi yomweyo, kapena mwina masekondi 20), komanso kuchuluka kwa mapaketi otumizidwanso:
[user@host ~]# netstat -s | grep retransmited; sleep 10; netstat -s | grep retransmited
17147 segments retransmited
17185 segments retransmited
Kuonjezera phokoso pamapaketi
Kuphatikiza pakutayika kwa paketi, mutha kutengera kuwonongeka kwa paketi: phokoso liziwoneka mwachisawawa. Tiyeni tiwononge paketi ndikuthekera kwa 50% popanda kulumikizana:
tc qdisc change dev lo root netem corrupt 50%
Timayendetsa script ya kasitomala (palibe chosangalatsa pamenepo, koma zidatenga masekondi a 2 kuti amalize), yang'anani kuchuluka kwa magalimoto:
Kutaya kwa magalimoto
[user@host ~]# tcpdump -i lo -nn port 12345
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
10:20:54.812434 IP 127.0.0.1.43666 > 127.0.0.1.12345: Flags [S], seq 2023663770, win 43690, options [mss 65495,sackOK,TS val 1037001049 ecr 0,nop,wscale 7], length 0
10:20:54.812449 IP 127.0.0.1.12345 > 127.0.0.1.43666: Flags [S.], seq 2104268044, ack 2023663771, win 43690, options [mss 65495,sackOK,TS val 1037001049 ecr 1037001049,nop,wscale 7], length 0
10:20:54.812458 IP 127.0.0.1.43666 > 127.0.0.1.12345: Flags [.], ack 1, win 342, options [nop,nop,TS val 1037001049 ecr 1037001049], length 0
10:20:54.812509 IP 127.0.0.1.43666 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 1037001049 ecr 1037001049], length 5
10:20:55.013093 IP 127.0.0.1.43666 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 1037001250 ecr 1037001049], length 5
10:20:55.013122 IP 127.0.0.1.12345 > 127.0.0.1.43666: Flags [.], ack 6, win 342, options [nop,nop,TS val 1037001250 ecr 1037001250], length 0
10:20:55.014681 IP 127.0.0.1.12345 > 127.0.0.1.43666: Flags [P.], seq 1:15, ack 6, win 342, options [nop,nop,TS val 1037001251 ecr 1037001250], length 14
10:20:55.014745 IP 127.0.0.1.43666 > 127.0.0.1.12345: Flags [.], ack 15, win 340, options [nop,nop,TS val 1037001251 ecr 1037001251], length 0
10:20:55.014823 IP 127.0.0.1.43666 > 127.0.0.5.12345: Flags [F.], seq 2023663776, ack 2104268059, win 342, options [nop,nop,TS val 1037001251 ecr 1037001251], length 0
10:20:55.214088 IP 127.0.0.1.12345 > 127.0.0.1.43666: Flags [P.], seq 1:15, ack 6, win 342, options [nop,unknown-65 0x0a3dcf62eb3d,[bad opt]>
10:20:55.416087 IP 127.0.0.1.43666 > 127.0.0.1.12345: Flags [F.], seq 6, ack 15, win 342, options [nop,nop,TS val 1037001653 ecr 1037001251], length 0
10:20:55.416804 IP 127.0.0.1.12345 > 127.0.0.1.43666: Flags [F.], seq 15, ack 7, win 342, options [nop,nop,TS val 1037001653 ecr 1037001653], length 0
10:20:55.416818 IP 127.0.0.1.43666 > 127.0.0.1.12345: Flags [.], ack 16, win 343, options [nop,nop,TS val 1037001653 ecr 1037001653], length 0
10:20:56.147086 IP 127.0.0.1.12345 > 127.0.0.1.43666: Flags [F.], seq 15, ack 7, win 342, options [nop,nop,TS val 1037002384 ecr 1037001653], length 0
10:20:56.147101 IP 127.0.0.1.43666 > 127.0.0.1.12345: Flags [.], ack 16, win 342, options [nop,nop,TS val 1037002384 ecr 1037001653], length 0
Zitha kuwoneka kuti mapaketi ena adatumizidwa mobwerezabwereza ndipo pali paketi imodzi yokhala ndi metadata yosweka: zosankha [nop, unknown-65 0x0a3dcf62eb3d,[bad opt]>. Koma chinthu chachikulu ndi chakuti pamapeto pake zonse zinayenda bwino - TCP inathana ndi ntchito yake.
Kubwereza kwa paketi
Chinanso chomwe mungachite nacho netem? Mwachitsanzo, yerekezerani mmene paketi inasokeraβkubwerezeranso paketi. Lamuloli limatenganso mfundo ziwiri: kuthekera ndi kulumikizana.
tc qdisc change dev lo root netem duplicate 50% 25%
Kusintha dongosolo la phukusi
Mukhoza kusakaniza matumbawo m'njira ziwiri.
Poyamba, mapaketi ena amatumizidwa nthawi yomweyo, ena onse amachedwa. Chitsanzo kuchokera pazolembedwa:
tc qdisc change dev lo root netem delay 10ms reorder 25% 50%
Ndi kuthekera kwa 25% (ndi kugwirizanitsa kwa 50%) paketi idzatumizidwa mwamsanga, ena onse adzatumizidwa ndi kuchedwa kwa 10 milliseconds.
Njira yachiwiri ndi pamene paketi iliyonse ya Nth imatumizidwa nthawi yomweyo ndi mwayi wopatsidwa (ndi malumikizanidwe), ndipo yotsalayo ndikuchedwa. Chitsanzo kuchokera pazolembedwa:
tc qdisc change dev lo root netem delay 10ms reorder 25% 50% gap 5
Phukusi lililonse lachisanu lili ndi mwayi wa 25% wotumizidwa popanda kuchedwa.
Kusintha Bandwidth
Kawirikawiri kulikonse kumene amalozerako , koma ndi chithandizo netem Mukhozanso kusintha mawonekedwe a bandwidth:
tc qdisc change dev lo root netem rate 56kbit
Gulu ili lipanga maulendo ozungulira localhost zowawa ngati kusewera pa intaneti kudzera pa modemu yoyimba. Kuphatikiza pa kuyika bitrate, muthanso kutengera mtundu wa protocol wa ulalo: ikani pamwamba pa paketi, kukula kwa selo, ndi mutu wa cell. Mwachitsanzo, izi zikhoza kutsanzira ndi bitrate 56 kbit / mphindi:
tc qdisc change dev lo root netem rate 56kbit 0 48 5
Kutengera nthawi yolumikizana
Mfundo ina yofunika mu dongosolo mayeso pamene kuvomereza mapulogalamu ndi nthawi. Izi ndizofunikira chifukwa m'machitidwe ogawidwa, pamene imodzi mwa mautumikiwa ili yolephereka, enawo ayenera kubwereranso kwa ena panthawi yake kapena kubwezera zolakwika kwa kasitomala, ndipo sayenera kungopachika, kuyembekezera kuyankha kapena kugwirizana. kukhazikitsidwa.
Pali njira zingapo zochitira izi: mwachitsanzo, gwiritsani ntchito kuseketsa komwe sikuyankha, kapena kulumikizana ndi njirayo pogwiritsa ntchito debugger, ikani malo opumira pamalo oyenera ndikuyimitsa njirayo (iyi mwina ndiyo njira yopotoka kwambiri). Koma chimodzi mwazodziwika kwambiri ndi madoko a firewall kapena makamu. Idzatithandiza ndi izi .
Kuti tichite ziwonetsero, tidzapanga firewall port 12345 ndikuyendetsa kasitomala athu. Mutha kuwombola mapaketi otuluka padokoli kwa wotumiza kapena mapaketi obwera pa wolandila. M'zitsanzo zanga, mapaketi omwe akubwera adzakhala ndi firewalled (timagwiritsa ntchito chain INPUT ndi kusankha --dport). Mapaketi oterowo akhoza kukhala DROP, REJECT kapena REJECT ndi TCP mbendera RST, kapena ndi ICMP host host yosafikirika (kwenikweni, khalidwe losasintha ndilo. icmp-port-osafikirika, ndipo palinso mwayi wotumiza yankho icmp-net-osafikirika, icmp-proto-osafikirika, icmp-net-yoletsedwa ΠΈ icmp-host-zoletsedwa).
Dontho
Ngati pali lamulo lokhala ndi DROP, mapaketi "angosowa".
iptables -A INPUT -p tcp --dport 12345 -j DROP
Timatsegula kasitomala ndikuwona kuti imaundana pamlingo wolumikizana ndi seva. Tiyeni tiwone magalimoto:
Kutaya kwa magalimoto
[user@host ~]# tcpdump -i lo -nn port 12345
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
08:28:20.213506 IP 127.0.0.1.32856 > 127.0.0.1.12345: Flags [S], seq 3019694933, win 43690, options [mss 65495,sackOK,TS val 1203046450 ecr 0,nop,wscale 7], length 0
08:28:21.215086 IP 127.0.0.1.32856 > 127.0.0.1.12345: Flags [S], seq 3019694933, win 43690, options [mss 65495,sackOK,TS val 1203047452 ecr 0,nop,wscale 7], length 0
08:28:23.219092 IP 127.0.0.1.32856 > 127.0.0.1.12345: Flags [S], seq 3019694933, win 43690, options [mss 65495,sackOK,TS val 1203049456 ecr 0,nop,wscale 7], length 0
08:28:27.227087 IP 127.0.0.1.32856 > 127.0.0.1.12345: Flags [S], seq 3019694933, win 43690, options [mss 65495,sackOK,TS val 1203053464 ecr 0,nop,wscale 7], length 0
08:28:35.235102 IP 127.0.0.1.32856 > 127.0.0.1.12345: Flags [S], seq 3019694933, win 43690, options [mss 65495,sackOK,TS val 1203061472 ecr 0,nop,wscale 7], length 0
Zitha kuwoneka kuti kasitomala amatumiza mapaketi a SYN okhala ndi nthawi yochulukirapo. Chifukwa chake tapeza cholakwika chaching'ono mwa kasitomala: muyenera kugwiritsa ntchito njirayo kukhazikitsa nthawi ()kuchepetsa nthawi yomwe kasitomala adzayesa kulumikizana ndi seva.
Timachotsa lamuloli nthawi yomweyo:
iptables -D INPUT -p tcp --dport 12345 -j DROPMutha kuchotsa malamulo onse nthawi imodzi:
iptables -F
Ngati mukugwiritsa ntchito Docker ndipo muyenera kuwotcha magalimoto onse opita ku chidebecho, ndiye kuti mutha kuchita motere:
iptables -I DOCKER-USER -p tcp -d CONTAINER_IP -j DROP
KANANI
Tsopano tiyeni tiwonjezere lamulo lofanana, koma ndi REJECT:
iptables -A INPUT -p tcp --dport 12345 -j REJECT
Wothandizira amatuluka pambuyo pa sekondi imodzi ndi cholakwika [Errno patsamba 111] Kulumikizana kwakana. Tiyeni tiwone kuchuluka kwa magalimoto a ICMP:
[user@host ~]# tcpdump -i lo -nn icmp
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
08:45:32.871414 IP 127.0.0.1 > 127.0.0.1: ICMP 127.0.0.1 tcp port 12345 unreachable, length 68
08:45:33.873097 IP 127.0.0.1 > 127.0.0.1: ICMP 127.0.0.1 tcp port 12345 unreachable, length 68
Zitha kuwoneka kuti kasitomala adalandira kawiri doko osafikirika kenako anamaliza ndi cholakwika.
KANIZA ndi tcp-reset
Tiyeni tiyese kuwonjezera njira --kana-ndi tcp-reset:
iptables -A INPUT -p tcp --dport 12345 -j REJECT --reject-with tcp-reset
Pankhaniyi, kasitomala nthawi yomweyo amachoka ndi cholakwika, chifukwa pempho loyamba lidalandira paketi ya RST:
[user@host ~]# tcpdump -i lo -nn port 12345
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
09:02:52.766175 IP 127.0.0.1.60658 > 127.0.0.1.12345: Flags [S], seq 1889460883, win 43690, options [mss 65495,sackOK,TS val 1205119003 ecr 0,nop,wscale 7], length 0
09:02:52.766184 IP 127.0.0.1.12345 > 127.0.0.1.60658: Flags [R.], seq 0, ack 1889460884, win 0, length 0
KANIZA ndi icmp-host-osafikirika
Tiyeni tiyese njira ina yogwiritsira ntchito REJECT:
iptables -A INPUT -p tcp --dport 12345 -j REJECT --reject-with icmp-host-unreachable
Wothandizira amatuluka pambuyo pa sekondi imodzi ndi cholakwika [Errno patsamba 113] Palibe njira yopezera alendo, tikuwona mumayendedwe a ICMP ICMP host 127.0.0.1 yosafikirika.
Mutha kuyesanso magawo ena a REJECT, ndipo ndimayang'ana kwambiri izi :)
Kutengera nthawi yofunsira
Chinthu china ndi pamene kasitomala adatha kulumikiza ku seva, koma sangathe kutumiza pempho kwa izo. Momwe mungasefe mapaketi kuti kusefa kusayambika nthawi yomweyo? Ngati muyang'ana pamsewu wa kulankhulana kulikonse pakati pa kasitomala ndi seva, mudzawona kuti pokhazikitsa mgwirizano, mbendera za SYN ndi ACK zokha zimagwiritsidwa ntchito, koma posinthanitsa deta, paketi yomaliza yopempha idzakhala ndi mbendera ya PSH. Imayimitsa yokha kuti isasungidwe. Mutha kugwiritsa ntchito chidziwitsochi kuti mupange fyuluta: ilola mapaketi onse kupatula omwe ali ndi mbendera ya PSH. Choncho, kugwirizana kudzakhazikitsidwa, koma kasitomala sangathe kutumiza deta ku seva.
Dontho
Kwa DROP lamulo lingawoneke motere:
iptables -A INPUT -p tcp --tcp-flags PSH PSH --dport 12345 -j DROP
Yambitsani kasitomala ndikuwona kuchuluka kwa magalimoto:
Kutaya kwa magalimoto
[user@host ~]# tcpdump -i lo -nn port 12345
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
10:02:47.549498 IP 127.0.0.1.49594 > 127.0.0.1.12345: Flags [S], seq 2166014137, win 43690, options [mss 65495,sackOK,TS val 1208713786 ecr 0,nop,wscale 7], length 0
10:02:47.549510 IP 127.0.0.1.12345 > 127.0.0.1.49594: Flags [S.], seq 2341799088, ack 2166014138, win 43690, options [mss 65495,sackOK,TS val 1208713786 ecr 1208713786,nop,wscale 7], length 0
10:02:47.549520 IP 127.0.0.1.49594 > 127.0.0.1.12345: Flags [.], ack 1, win 342, options [nop,nop,TS val 1208713786 ecr 1208713786], length 0
10:02:47.549568 IP 127.0.0.1.49594 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 1208713786 ecr 1208713786], length 5
10:02:47.750084 IP 127.0.0.1.49594 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 1208713987 ecr 1208713786], length 5
10:02:47.951088 IP 127.0.0.1.49594 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 1208714188 ecr 1208713786], length 5
10:02:48.354089 IP 127.0.0.1.49594 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 1208714591 ecr 1208713786], length 5
Tikuwona kuti kulumikizana kwakhazikitsidwa ndipo kasitomala sangathe kutumiza deta ku seva.
KANANI
Pankhaniyi khalidwe lidzakhala lofanana: kasitomala sangathe kutumiza pempho, koma adzalandira ICMP 127.0.0.1 tcp port 12345 yosafikirika ndi kuonjezera nthawi pakati pa zopempha kutumizidwanso mochulukira. Lamulo likuwoneka motere:
iptables -A INPUT -p tcp --tcp-flags PSH PSH --dport 12345 -j REJECT
KANIZA ndi tcp-reset
Lamulo likuwoneka motere:
iptables -A INPUT -p tcp --tcp-flags PSH PSH --dport 12345 -j REJECT --reject-with tcp-reset
Ife tikudziwa kale kuti pamene ntchito --kana-ndi tcp-reset kasitomala adzalandira paketi ya RST poyankha, kotero kuti khalidwelo likhoza kunenedweratu: kulandira paketi ya RST pamene kugwirizana kumatanthawuza kuti socket imatsekedwa mosayembekezereka kumbali inayo, zomwe zikutanthauza kuti kasitomala ayenera kulandira. Kulumikizana kubwezeretsedwa ndi anzawo. Tiyeni tiyendetse script yathu ndikuwonetsetsa izi. Ndipo izi ndi momwe magalimoto adzawonekera:
Kutaya kwa magalimoto
[user@host ~]# tcpdump -i lo -nn port 12345
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
10:22:14.186269 IP 127.0.0.1.52536 > 127.0.0.1.12345: Flags [S], seq 2615137531, win 43690, options [mss 65495,sackOK,TS val 1209880423 ecr 0,nop,wscale 7], length 0
10:22:14.186284 IP 127.0.0.1.12345 > 127.0.0.1.52536: Flags [S.], seq 3999904809, ack 2615137532, win 43690, options [mss 65495,sackOK,TS val 1209880423 ecr 1209880423,nop,wscale 7], length 0
10:22:14.186293 IP 127.0.0.1.52536 > 127.0.0.1.12345: Flags [.], ack 1, win 342, options [nop,nop,TS val 1209880423 ecr 1209880423], length 0
10:22:14.186338 IP 127.0.0.1.52536 > 127.0.0.1.12345: Flags [P.], seq 1:6, ack 1, win 342, options [nop,nop,TS val 1209880423 ecr 1209880423], length 5
10:22:14.186344 IP 127.0.0.1.12345 > 127.0.0.1.52536: Flags [R], seq 3999904810, win 0, length 0
KANIZA ndi icmp-host-osafikirika
Ndikuganiza kuti ndizodziwikiratu kwa aliyense kuti lamuloli lidzawoneka bwanji :) Khalidwe la kasitomala pankhaniyi lidzakhala losiyana pang'ono ndi losavuta KUGANIZA: kasitomala sangawonjezere nthawi pakati pa kuyesa kutumizanso paketi.
[user@host ~]# tcpdump -i lo -nn icmp
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 262144 bytes
10:29:56.149202 IP 127.0.0.1 > 127.0.0.1: ICMP host 127.0.0.1 unreachable, length 65
10:29:56.349107 IP 127.0.0.1 > 127.0.0.1: ICMP host 127.0.0.1 unreachable, length 65
10:29:56.549117 IP 127.0.0.1 > 127.0.0.1: ICMP host 127.0.0.1 unreachable, length 65
10:29:56.750125 IP 127.0.0.1 > 127.0.0.1: ICMP host 127.0.0.1 unreachable, length 65
10:29:56.951130 IP 127.0.0.1 > 127.0.0.1: ICMP host 127.0.0.1 unreachable, length 65
10:29:57.152107 IP 127.0.0.1 > 127.0.0.1: ICMP host 127.0.0.1 unreachable, length 65
10:29:57.353115 IP 127.0.0.1 > 127.0.0.1: ICMP host 127.0.0.1 unreachable, length 65
Pomaliza
Sikoyenera kulemba kunyoza kuyesa kuyanjana kwa ntchito ndi kasitomala wopachikidwa kapena seva; nthawi zina ndizokwanira kugwiritsa ntchito zofunikira zomwe zimapezeka mu Linux.
Zothandizira zomwe zafotokozedwa m'nkhaniyi zili ndi kuthekera kochulukirapo kuposa momwe zidafotokozedwera, kotero mutha kupeza zina mwazomwe mungagwiritse ntchito. Payekha, nthawi zonse ndimakhala ndi zokwanira zomwe ndidalemba (makamaka, ngakhale zochepa). Ngati mugwiritsa ntchito izi kapena zofananira poyesa kampani yanu, chonde lembani momwe ndendende. Ngati sichoncho, ndiye ndikuyembekeza kuti pulogalamu yanu ikhala bwino ngati mungaganize zoyesa pamavuto a netiweki pogwiritsa ntchito njira zomwe zaperekedwa.
Source: www.habr.com